Heterogeneous Copper Catalyst Research Articles

Ligand-free coupling of phenols and alcohols with aryl halides by a recyclable heterogeneous copper catalyst

A novel and efficient heterogeneous catalyst system based on CuI immobilized on a MOF material for the O-arylation of phenols and alcohols with aryl halides under ligand-free conditions is reported.

A reusable polymer supported copper catalyst for the C–N and C–O bond cross-coupling reaction of aryl halides as well as arylboronic acids

A simple and industrially viable protocol for C–N and C–O coupling was reported here. The polymer supported heterogeneous copper catalyst was prepared from chloromethyl polystyrene using a simple procedure. O-Arylation of substituted phenols with various aryl halides was achieved using this copper catalyst in DMSO medium. This heterogeneous copper catalyst, also efficiently works for the N-arylation of N–H heterocycles with aryboronic acids in methanol. This catalyst was also effective in amination reaction of primary amines with aryl halides as well as arylboronic acids in DMSO medium. The effects of solvent, base and temperature for the O-Arylation and amination reactions were reported. Further, the catalyst can be easily recovered quantitatively by simple filtration and reused up to several times without sufficient loss of its catalytic activity.

Silver cluster-promoted heterogeneous copper catalyst for N-alkylation of amines with alcohols

A series of metal(M)-loaded Al2O3 catalysts (M/Al2O3) and bimetallic catalysts, CuxAg1−x/Al2O3 with different compositions, Cu0.95Ag0.05/MOx with different supports (MOx), and Cu0.95M′0.05/Al2O3 with different promoter (M′), were prepared by an impregnation method, followed by H2-reduction at 600 °C. For the N-alkylation of amines with alcohols, Al2O3-supported copper–silver bimetallic catalysts with a Cu/Ag molar ratio of 95/5 (Cu0.95Ag0.05/Al2O3) was found to be the most effective heterogeneous catalyst. The alkylation of anilines and aliphatic amines with various alcohols (benzyl and aliphatic alcohols) was achieved with a small amount of the catalyst (1 mol%). Mechanistic studies show that the reaction proceeds through a hydrogen-borrowing mechanism initiated by alcohol dehydrogenation as the rate-limiting step. Structural studies indicate that small Ag nanoclusters are supported on Cu nanoparticles possibly through Ag–O–Cu bonds at the silver–copper boundary. This bimetallic structure can be crucial to an effective promotion of the alcohol dehydrogenation and hydride transfer to the imines.

A Click procedure with heterogeneous copper to tether technetium-99m chelating agents and rhenium complexes. Evaluation of the chelating properties and biodistribution of the new radiolabelled glucose conjugates

An efficient protocol was developed to tether chelating agents and rhenium complexes onto a glucoside scaffold with a heterogeneous copper catalyst via click chemistry. The supported catalyst avoids the formation of unwanted copper complexes during the cyclisation step. The possibility to graft a pre-chelated M(CO) 3 core by click chemistry onto a biomolecule was highlighted for the first time. 99mTc(CO) 3-glucoconjugates displayed excellent in vitro stability, a fast in vivo blood clearance and a low specific organ uptake or long-term retention in spleen and stomach.

ChemInform Abstract: Use of Heterogeneous Copper Catalysts and of Acidic Mixed Oxides in Organic Synthesis

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heterogenization of functionalized Cu(II) and VO(IV) Schiff base complexes by direct immobilization onto amino-modified SBA-15: Styrene oxidation catalysts with enhanced reactivity

Two functionalized copper(II) and oxovanadium(IV) Schiff base complexes of type [M(N 2O 2), M = Cu, VO] bearing chloromethyl groups were respectively synthesized, directly anchored onto amino-modified SBA-15 materials and examined as catalysts for styrene oxidation. The purity of each ligand was confirmed by 1H NMR, FT-IR and elemental analysis. XRD, N 2 adsorption/desorption and TEM results indicated that the mesoporous structure of SBA-15 remained intact throughout the grafting procedure. FT-IR, UV–vis spectroscopy plus TG–DTA data demonstrated the incorporation of copper(II) and oxovanadium(IV) complexes on amino-modified SBA-15. ICP-AES, SEM-EDX combined with XPS data further showed the different anchorage status of copper(II) and oxovanadium(IV) species on amino-modified SBA-15. The copper(II) Schiff base complex was anchored through the coordination of copper atom with the nitrogen atom of the amino group modified on the SBA-15 external surface. The oxovanadium(IV) Schiff base complex, however, was covalently anchored on SBA-15 via the condensation reaction of the chloromethyl group of the Schiff base with the amino group from the modified SBA-15 matrix. The catalytic properties of supported copper(II) and oxovanadium(IV) complexes in the oxidation of styrene with air or H 2O 2 as oxidant were investigated and compared with the properties of their homogeneous analogues. It was found that both heterogeneous copper(II) and oxovanadium(IV) catalysts were more active than their homogeneous analogues and that the product selectivity varied in cases of different oxidants. The supported oxovanadium(IV) complex showed high yield of styrene oxide (56.0%) and good recoverability when using air as oxidant.

Synthesis of (2E)-2-methyl-3-(4-([4-(quinolin-2-ylmethoxy)phenyl]sulfanyl)phenyl)prop-2-enoic acid (VUFB 20609) and 2-methyl-3-(4-([4-(quinolin-2-ylmethoxy)phenyl]sulfanyl)phenyl)propanoic acid (VUFB 20584) as potential antileukotrienic agents.

The syntheses of (2E)-2-methyl-3-(4-([4-(quinolin-2-ylmethoxy)phenyl]sulfanyl)phenyl) prop-2-enoic acid (VUFB 20609) and racemic 2-methyl-3-(4-([4-(quinolin-2-ylmethoxy) phenyl]sulfanyl)phenyl)propanoic acid (VUFB 20584) as new potential antileukotrienic drugs are described. Due to a low reactivity of the 4-substituted aryl bromides (coupling of the 4-substituted aryl bromides do not provide an activating functional group with 4-methoxybenzene-1-thiol), special conditions, in particular specific heterogeneous copper catalysts, were used. Catalytic hydrogenation of the conjugated double bond on Pd/C in the presence of the sulfanyl group is discussed. In-vitro cytotoxicity testing was performed using a microplate colorimetric acid phosphatase assay. Antiplatelet activity was evaluated using an in-vitro test in human platelet-rich plasma. Some substances inhibited arachidonic acid-induced platelet aggregation.

Bifunctional copper catalysts for an atom efficient ether synthesis

A direct etherification of aromatic ketones and aliphatic alcohols into the corresponding asymmetrical ethers by the use of a bifunctional heterogeneous copper catalyst is described. The reaction protocol reveals to be versatile and convenient respect to the traditional ether synthesis for both environmental and practical concerns.

Modeling of a pilot-scale trickle bed reactor for the catalytic oxidation of phenol

A mathematical model was developed to simulate the catalytic wet air oxidation (CWAO) of aqueous phenol in a trickle bed reactor (TBR). Both ‘axial dispersion’ and ‘plug flow’ models were proposed. ‘Steady-state’ mass transfers across different phases inside the reactor have all been considered in parallel with oxidation reactions catalyzed by heterogeneous copper catalyst supported on activated carbon. The changes in the concentrations of oxygen and phenol in various phases were thus depicted as a function of bed length. In order to validate the accuracy of the established TBR model, a series of experiments on phenol oxidation were performed on a pilot-scale TBR containing 5.6 l of catalysts. The model was found able to give satisfactory predictions for nearly half of all the runs. The discrepancies between the experimental and modeling results were investigated for the less promising runs. It was also noticed that similar simulation results could be attained from ‘axial dispersion’ model against ‘plug flow’ model. Following the discussion on the changes of phenol and oxygen concentrations in the various phases, it is finally concluded that the performance of the TBR of this study depends largely on gas-to-liquid mass transfer process. Further suggestions with regards to reactor optimization are also proposed on the basis of experimental outcome.

Copper Catalyzed Coupling of α-Bromocarboxylate with ω-Lactam

This paper especially deals with the problem associated with the reaction of α-bromocarboxyl compound and 5- membered ω-lactam ring. Specific heterogeneous copper catalyst was used to achieve the C – N nucleophilic coupling. Synthetic pathway of ethyl-6-(2,5-dioxopyrrolidin-1-yl)-2-(2-oxopyrrolidin-1-yl)hexanoate as the key intermediate of new potential transdermal enhancers is described. All generated compounds were characterized by NMR and IR spectroscopy. Keywords: Copper catalyst, C, –, N coupling, ω-lactam derivatives, penetration enhancers

Facile Access to an Efficient Solid‐Supported Click Catalyst System Based on Poly(ethyleneimine)

A novel heterogeneous copper(I) catalyst system, which is based on readily available poly(ethyleneimine), has been used as a recyclable catalyst for Cu(I) catalyzed "click" 1,3 dipolar cycloaddition reactions of azides and alkynes in organic media. Branched poly(ethyleneimine) was first methylated and then cross-linked with 1,9-dibromononane. Subsequently, after the immobilization of Cu(I)Br, this system was applied for heterogeneous copper catalyzed click chemistry of a few model reagents and polymeric compounds.

ChemInform Abstract: Heterogeneous Copper Catalyst for the Cycloaddition of Azides and Alkynes Without Additives under Ambient Conditions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Heterogeneous Copper Catalyst for the Cycloaddition of Azides and Alkynes without Additives under Ambient Conditions

A new copper catalyst was developed by immobilizing copper nanoparticles in aluminum oxyhydoxide fiber. The catalyst showed high catalytic activity for the (3+2) Huisgen cycloaddition of nonactivated alkynes as well as activated ones with various azides at room temperature. The catalyst was recycled five times without significant loss of activity.

Investigation of the generation of hydroxyl radicals and their oxidative role in the presence of heterogeneous copper catalysts

The presence and impact of hydroxyl radicals generated via the catalytic decomposition of H 2O 2 over heterogeneous copper catalysts were investigated by using two detection methods, an electron spin resonance-spin trapping method and a chemical probe method. Detection of the (5,5-dimethyl-1-pyrroline-N-oxide)–OH adduct signal and formation of 4-chlorocatechol during the oxidation of a 4-chlorophenol substrate demonstrated that the three heterogeneous copper catalysts employed here (CuO, Cu/Al 2O 3 and CuO · ZnO/Al 2O 3) were capable of generating hydroxyl radicals in combination with H 2O 2. The oxidative mechanism of the hydroxyl radical in the presence of heterogeneous copper catalysts is discussed with regard to the further oxidation of the (5,5-dimethyl-1-pyrroline-N-oxide)–OH adduct and hydroxylated products of 4-chlorophenol oxidation. Interestingly, integration of the 5,5-dimethyl-1-pyrroline-N-oxide–OH adduct signal could not be used to reliably measure the total amount of hydroxyl radicals generated as a result of oxidative attack on the adduct. This may be as a result of locally higher hydroxyl radical concentrations in the presence of a heterogeneous catalyst leading to further unwanted oxidation of the (5,5-dimethyl-1-pyrroline-N-oxide)–OH.

Catalytic Wet Oxidation of Ferulic Acid (A Model Lignin Compound) Using Heterogeneous Copper Catalysts

Catalytic wet oxidation (CWO) of ferulic acid (a model lignin compound) was investigated at low temperature and pressure (100 °C, 172 kPa P O2). Nine homogeneous catalysts were screened at three different catalyst loadings. Homogeneous copper ions were observed to be the most active catalysts; various copper based heterogeneous catalysts were also prepared and tested. The most active catalyst was Cu−Ni−Ce−Al2O3; however, this catalyst also exhibited the highest extent of copper leaching. Cu−Mn−Al2O3 was the most stable catalyst tested and was second only to Cu−Ni−Ce−Al2O3 in terms of activity among nine heterogeneous catalysts studied. Heterogeneous catalytic activity compared with the activity due to leached metal ions was observed to be dominant for both of the above-mentioned catalysts.

The beneficial role of use of ultrasound in heterogeneous Fenton-like system over supported copper catalysts for degradation of p-chlorophenol

A heterogeneous sono-catalytic system with addition of hydrogen peroxide ( U S H 2 O 2 + Cat . ) was employed for the degradation of 200 ppm of p-chlorophenol (4-CP) at 25 °C and 100 W of ultrasound power. One thousand and six hundred parts per million of initial hydrogen peroxide (H 2O 2) concentration and 1 g/L of catalyst loading over three heterogeneous copper catalysts, CuO, Cu/Al 2O 3 (Cu/Al) and CuO·ZnO/Al 2O 3 (Cu/Zn) was used. The benefits of ultrasound in a heterogeneous catalytic system were evaluated. A considerable synergistic effect of the U S H 2 O 2 + Cat . system was only achieved with supported catalysts (Cu/Al and Cu/Zn) possibly due to good dispersion of catalysts as a result of catalyst size reduction during ultrasound irradiation. Moreover, between the two supported copper catalysts, the Cu/Al provided promising catalytic performance by giving higher 4-CP and TOC removal accompanied with efficient H 2O 2 consumption. Experiments with a homogeneous copper catalyst revealed that use of ultrasound in a homogeneous system shows an adverse effect on decomposition of 4-CP.

Antimicrobial Evaluation of Some Arylsulfanylpyrazinecarboxylic Acid Derivatives

The radical-ionic coupling of chloropyrazine-2-carboxylic acid derivatives with methoxybenzenethiols, carried out in the presence of a heterogeneous copper catalyst, provided the series of 6- or 5- or 3-(4-methoxyphenyl)sulfanyl-pyrazine-2-carboxylic acid derivatives as well as 6- or 5- or 3-(3-methoxyphenyl)sulfanylpyrazine-2-carboxylic acid derivatives. The prepared compounds were evaluated as potential antifungal agents and new antituberculotics. Their preliminary in vitro evaluation of antimycobacterial activity according to the international program with the Tuberculosis Antimicrobial Acquisition and Coordinating Facility (TAACF) is presented. Several compounds showed an interesting activity in the preliminary screening with a percentage growth inhibition of the virulent Mycobacterium tuberculosis H(37)Rv between 50 to 100% at the concentration 6.25 microg/mL. Structure-activity relationships among the chemical structure, the physical properties and the biological activities of the evaluated compounds are discussed in the article.

Heterogeneous Copper Catalysts for Enantioselective C-H Carbene Insertion

Heterogeneous Copper Catalysts for Enantioselective C-H Carbene Insertion

Simple and Efficient Heterogeneous Copper Catalysts for Enantioselective C−H Carbene Insertion

Immobilized box-Cu complexes are able to efficiently catalyze the insertion of a carbene, from methyl phenyldiazoacetate, into C-H bonds of THF, with high enantioselectivity (up to 88% ee). The immobilization not only allows recovery and reuse of the enantioselective catalyst but also provides an improvement in the selectivities from the values obtained in solution, probably due to a confinement effect of the bidimensional support. [reaction: see text].

4‐Substituted Aryl Bromides Coupling with 4‐Methoxybenzene‐1‐thiol by Means of Copper Catalysts.

AbstractFor Abstract see ChemInform Abstract in Full Text.